Use of PHP built-in functions

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Release: 2024-04-14 08:48:01
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PHP built-in functions provide the following functions: 1. Type conversion: is_numeric(), floatval(), strval(), intval(); 2. String processing: strlen(), substr(), ucwords(), strtolower(); 3. Array processing: count(), in_array(), array_merge(), array_filter(); 4. Mathematical functions: round(), pow(), sqrt(), max(); 5. Date and Time functions: time(), date(), strtotime(), mktime(). Practical example: The code snippet uses the filter_var() function to verify the validity of an email address.

PHP 内置函数的使用

Usage of PHP built-in functions

PHP built-in functions are predefined functions that can be used for various purposes without user definition. operate. They provide powerful features that simplify programming tasks and increase code reusability.

Type conversion function

  • is_numeric(): Check whether the variable is a number.
  • floatval(): Convert the variable to a floating point number.
  • strval(): Convert the variable to a string.
  • intval(): Convert a variable to an integer.

String processing function

  • strlen(): Returns the length of the string.
  • substr(): Extract a substring from a string.
  • ucwords(): Capitalize the first letter of the words in the string.
  • strtolower(): Convert the string to lowercase.

Array processing function

  • count(): Returns the number of elements in the array.
  • in_array(): Check whether an element exists in the array.
  • array_merge(): Merge two or more arrays.
  • array_filter(): Filter elements that meet specific conditions from the array.

Mathematical functions

  • round(): Rounds a number to the specified number of digits.
  • pow(): Calculate the power of a number.
  • sqrt(): Calculates the square root of a number.
  • max(): Returns the maximum of two or more numbers.

Date and time functions

  • time(): Get the current timestamp.
  • date(): Format the timestamp into a date and time string.
  • strtotime(): Parses date and time strings into timestamps.
  • mktime(): Creates a timestamp based on the specified date and time parameters.

Practical Case: Validating User Input

The following code uses a built-in function to validate the email address entered by the user:

$email = 'john@example.com';

if (!filter_var($email, FILTER_VALIDATE_EMAIL)) {
  echo '无效的电子邮件地址';
} else {
  echo '有效的电子邮件地址';
}
Copy after login

This code The snippet uses the filter_var() function to verify that $email is a valid email address and outputs the message accordingly.

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